The present invention relates generally to power generation and delivery and more particularly relates to a system for generating power and delivering it over the data communication cabling infrastructure within a facility.
Currently, the infrastructure making up Ethernet Local Area Networks (LANs) and Wide Area Networks (WANs) is constructed to carry and distribute high bit rate data communication signals between network devices. The network devices or elements, may include, for example, hubs, switches, bridges, routers, interconnection equipment, various devices that are equipped with Network Interface Cards (NICs), data servers, desktop PCs, portable PCs and other various network equipment. What all these devices have in common, among other things, is that they all require electrical power in order to operate. In each case, the electrical power consumed by these devices is supplied by internal or external batteries or by AC power supplied from a power utility.
Today, every network element device that is not self energized, i.e., includes an internal or external battery, requires a connection to a source of electrical power in addition to one or more network connections. The requirement of network devices to connect to a source of electrical power complicates installation and makes it more costly. In addition, it limits the location of network elements to locations where electrical power connections and data network connections are available. Ultimately, two separate networks must be built and maintained, wherein each network is connected to the network device. One network supplies electrical power distribution and the other network supplies connectivity to the data communications network.
Further, for network devices to operate during partial or complete electrical power supply interruption or failure, each network device must either incorporate an internal battery backup system or must be connected to an Uninterruptable Power Supply (UPS). Depending on the application, such as with IP or LAN telephones, the number of network devices that must operate during building power failures may be very high.
Thus, it would be desirable to eliminate the need for each network device that does not operate from a battery to be connected to a source of AC utility power, i.e., a standard AC electrical receptacle, in addition to a network connection. This would significantly reduce the number of electrical cables, AC receptacles and associated connections thereby simplifying the installation of network devices. In addition, this would also provide a cost effective means for providing an uninterruptable power source to multiple network devices.
It is important to point out that the data communications network infrastructure was primarily designed and optimized to carry high bandwidth low power data communications signals and was not designed to deliver electrical power. The IEEE 802.3 standard requires that the electrical voltages carried over the transmitting cable be isolated and balanced in reference to earth ground at both ends. Category 3 to 5 LAN cables, RJ-45 connectors, the line interface of network devices and all IEEE 802.3 compatible devices within the network were not designed to carry electrical power at a sufficient level to operate the majority of network devices.
Therefore, any solution that uses the LAN infrastructure to simultaneously distribute electrical power and provide network data communications should address the following points: (1) electrical power distribution over the LAN infrastructure should neither increase the network bit error rate (BER) beyond permissible levels nor disturb normal data communications in any way; (2) electrical power on the LAN infrastructure should not introduce any possibility of harm or risk to users and network maintenance personnel; (3) electrical power over the LAN infrastructure should not harm or cause damage to standard LAN equipment which is not designed to receive power from the data communications network; and (4) the addition of electrical power over the data communications network should not degrade the reliability of the network.
Systems for delivering data communication signals over power networks are known in the art. Power line carrier systems are well known and function to superimpose relatively high frequency data signals over low frequency power cabling. These systems, however, are designed to operate over power lines that are very different from the LAN. The LAN medium is designed and constructed to carry data communication signals. Thus, the cables, connectors, line interface circuitry and terminal devices are not designed to handle high levels of electrical power. This is very different from superimposing low energy level data communication signals over power line networks.
A block diagram illustrating an example prior art data communications network wherein network devices are coupled to the AC main utility power is shown in FIG. 1. This example network is presented to illustrate the various network elements that are typically found in a LAN environment. The network, generally referenced 10, comprises a combination WAN and/or LAN backbone 12 coupled to an IP telephony server 14 and/or to one or more other service providers 15 and also to a LAN bridge/router 16 which is connected to a source of AC power via electrical plug 22. The IP telephony server 14 functions to provide telephone service for a plurality of Internet or IP telephones 52, 36, 28.
The LAN bridge/router 16 is coupled to two LAN hubs or switches 18, 20. IP telephones 28, 36, laptop or other portable computer 32 and desktop computer 40 are coupled to LAN hub/switch 18 via network data connections 31. LAN hub/switch 18 is connected to a separate source of AC power via electrical plug 24. IP telephone 28, 36, portable computer 32 and desktop computer 40 are connected to a source of AC power via electrical plugs 30, 38, 34, 42, respectively.
The LAN hub/switch 20 is also coupled to a separate source of AC power via electrical plug 26. A video camera 44 (e.g., standard video camera or Web camera), portable computer 48 and IP telephone 52 are coupled to LAN hub/switch 20 via network data only connections 47. Video camera 44, portable computer 48 and IP telephone 52 are connected to a source of AC power via electrical plugs 46, 50, 54, respectively.
It is noted that each network device requires a separate data communications connection and a connection to a source of electrical power. The data networking connection is made in the normal manner using standard LAN cabling to conventional hubs, switches, routers, etc. Electrical power to each network device is supplied via a plurality of AC mains receptacles. Thus, each network device must be provided with at least two utility hook ups: one to the data communications network and the second to the AC electrical power network.
The present invention is a system for generating, delivering and distributing electrical power to network elements over a data communication network infrastructure within a building, campus or enterprise. Consolidating power distribution and data communications over a single network serves to (1) both simplify and reduce the cost of network element installation and (2) provide a means of supplying uninterrupted or backup power to critical network devices in the event of a power failure.
Network installations that utilize the present invention can be simplified and are less costly because the number of required power cables, power receptacles and AC power supplies or adapters is greatly reduced. In addition, network devices, terminals and other networking equipment can be placed without regard to the existence of or the location of AC receptacles.
The system of the present invention also provides for a significant cost reduction in providing uninterruptable backup electrical power to critical network devices and terminals in the event of a power supply failure or interruption. This is due to the fact that distributing backup power, i.e., power from an uninterruptable power supply, from a few points in the network via the LAN infrastructure is far more efficient than connecting each critical network element to its own dedicated UPS or to a backed up power line. An assumption that is valid most of the time is that only a relatively small portion of the network elements, e.g., hubs, switches, routers, etc., need to be connected to a dedicated source of uninterruptable power while the remainder of the critical network devices receive their operating power via the LAN infrastructure.
Another benefit of the system of the present invention is that the safety requirements and cost of network terminal equipment can be reduced since electrical power can now be fed from low voltages delivered over the LAN infrastructure. This is in contrast to the current method of providing an internal or external 110/220 VAC power supply that requires that the network device receive certification by one or more testing organizations such as Underwriters Laboratory (UL). In the case of IP telephony, which is becoming more and more popular, providing power over the LAN permits the IP telephone to have a source of uninterruptable power just as ordinary analog based telephones connected to the PSTN enjoy today.
The disclosure presented hereinbelow describes an apparatus for and methods for generating, delivering and managing electrical power over LAN network infrastructures that are primarily designed for digital communications purposes. The invention functions to reduce any possible disturbances to the data communications and to maintain compatibility with the IEEE 802.3 and other relevant standards.
The power over LAN system of the present invention operates with high bandwidth data communication networks, i.e., 10 Mbps, 100 Mbps, 1000 Mbps, which are naturally more susceptible to noise, network bandwidth, near end and alien crosstalk. In addition, the present invention takes into account the limitation in cable length imposed by modern LANs, i.e., hundreds of meters versus kilometers in PSTN, ISDN and HDSL communication lines. The invention discloses novel remote power feeding methods that are better suited for shorter haul cable runs.
Further, the electrical power distributed over the LAN can be delivered as DC or low frequency AC voltages which in either case will interfere minimally with data communications signals. The electrical power delivered over the data communications cable can be transmitted using one or more spare pairs in the cable. Ethernet communications requires 2 pairs (4 conductors) to implement. If 4 pair (8 conductor) Category 3, 4 or 5 cable is used, than 2 pairs are not used for data communications. The electrical power can be transmitted using one or more of the cable wire pairs. Alternatively, if the data cable comprises only two pair, then the electrical power is distributed using one or two of the available pairs, i.e., the receive and transmit wires. Thus, in accordance with the invention, power can be delivered over any combination of used and/or unused twisted pair wires in the data communication cable.
There is provided in accordance with the present invention a system for distributing electrical power over a data communication cabling infrastructure to one or more electrical power consuming network devices comprising a data communications cabling network, a source of electrical power, at least one power/data combiner coupled to the source of electrical power and to the data communications cabling network, the at least one power/data combiner operative to generate and inject a low frequency power signal onto a data communications signal received from the data communications cabling network so as to yield a combined power/data signal which is subsequently output onto the data communications cabling network and at least one power/data splitter adapted to receive the combined power/data signal and to extract and separate therefrom the original data communication signal and the low frequency power signal.
The data communications network may comprise an Ethernet based Local Area Network (LAN). The power/data combiner can be implemented as a standalone unit, integrated into a Local Area Network (LAN) hub or into a Local Area Network (LAN) switch.
The power/data combiner may comprise a plurality of data only input ports and a plurality of data plus power output ports, each data in port and data plus power output port forming a separate channel. In addition, the power/data combiner is adapted to receive electrical from an AC mains power receptacle, an uninterruptable Power Supply (UPS) or an another power/data combiner.
The power/data combiner comprises means for filtering high frequency noise and ripple, for sensing the current in the low frequency power signal, for connecting and disconnecting the low frequency power signal to and from the combined output power/data signal and for detecting no-load and overload conditions on the combined output power/data signal.
The system further comprises a management unit for monitoring and provisioning, via the data communications cabling network, the power/data combiners and power/data splitters located in the data communications cabling network.
The power/data splitter can be implemented as a standalone unit or integrated into a network device. The power/data combiner may comprise an AC/DC or DC/DC power converter for converting the extracted low frequency power signal into one or more output voltages.
There is also provided in accordance with the present invention a method for distributing electrical power over a data communication cabling infrastructure to one or more electrical power consuming network devices, the method comprising the steps of generating a low frequency power signal from a source of electrical power, injecting the low frequency power signal into a data communications signal being carried over the data communications cabling network so as to generate a combined power/data signal, transmitting the combined power/data signal onto the data communications cabling network, receiving the combined power/data signal carried over the data communication cabling network and splitting the combined power/data signal so as to yield the data communication signal separated from the low frequency power signal.
There is further provided in accordance with the present invention a system for distributing electrical power over a data communication cabling infrastructure to one or more electrical power consuming network devices comprising a data communications cabling network, a source of electrical power, power supply means for generating a low frequency power signal from the source of electrical power, combiner means coupled to the data communications cabling network, the combiner means for injecting the low frequency power signal onto a data communications signal being carried over the data communications cabling network so as to yield a combined power/data signal, regulator means for regulating the injection of the low frequency power signal onto the data communications signal, the regulation including, but not limited to, ceasing the injection of the low frequency power signal and limiting its current, extraction means for extracting the low frequency power signal from the combined power/data signal and for outputting the original data communication signal and the low frequency power signal.